Department of Chemical Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran
Department of Chemical Engineering, Shahrood Branch, Islamic Azad University, Shahrood, Iran
This research evaluated the efficiency of combined anaerobic-aerobic processes for the treatment of slaughterhouse wastewater. The anaerobic reactor consists of a 3.95 L Plexiglas column with 60 mm diameter and 140 cm height. The cylindrical particles of polyvinyl chloride with 2 mm diameter and 1250 kg m-3 density packed to 60 cm of column were used as biomass saving material. The designed aerobic reactor also has a Plexiglas column with 10 cm internal diameter, 90 cm height and 60 cm useful height. Anaerobic fluid bed and aerobic mobile bed reactors were exploited for retention times of 18, 24, 32, 40 and 48 h. The efficiency of total suspended solids, biological oxygen demand and chemical oxygen demand removing were evaluated in different stages. Under the applied condition, chemical oxygen demand, biological oxygen demand and suspended solids were removed by 85.94, 92 and 66%, respectively. Maximum methane production of 3765 mL per day was obtained after 31 h at the residence time of 18 h. The anaerobic reactor plays very important role in reduction of the chemical oxygen demand, and the aerobic reactor is necessary to clear the anaerobic treated wastewater and ensure the quality of the final waste.